ok experts...time for a definitive posting. Black Pad is ? (any photos?) Caused by: 1) ? 2) ? Fixed By: 1) ? 2) ? A little while back a new customer asked me what RoHS finish I prefer. I told him that I liked ENIG for a few reasons over silver or tin. He quickly asked me "Aren't you worried about black pad?" Being that I recently had a tetanus shot and take a daily multi-vitamin I thought I was in pretty good shape so I said that I was not worried about it. That being said...I too would like to know more about this issue since I've used gold finishes for many years now and have never had an issues with it. I've seen soldering issues due to the type of solder used or thickness of gold but nothing like this issue. _____________________________________ Kenneth J. Wood President Saturn PCB Design, Inc. [log in to unmask] 2737 Bishop Lane Phone:(407) 340-2668 Deltona, Fl 32725 Fax: (386) 789-2765 www.saturnpcb.com -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /* Sent: Thursday, November 20, 2008 6:18 PM To: [log in to unmask] Subject: Re: [TN] black pad Agreed, the prescription for the fix will be different. Werner -----Original Message----- From: Igoshev, Vladimir <[log in to unmask]> To: [log in to unmask] Sent: Thu, 20 Nov 2008 5:52 pm Subject: Re: [TN] black pad Hi Werner, I completely agree on what we disagree on :-) I think that the same appearnce can (and is in that particuar case) be caused by completely different phenomena, therefore the recepie to fix/avoid it will be different. Regards, Vladimir ----- Original Message ----- From: TechNet <[log in to unmask]> To: [log in to unmask] <[log in to unmask]> Sent: Thu Nov 20 17:28:06 2008 Subject: Re: [TN] black pad Hi Vladimir, That is where we disagree--the definition of 'Black Pad.' I define it as the phenomenon root cause regardless of what caused it--that is not to say that who caused it is unimportant. Werner -----Original Message----- From: Igoshev, Vladimir <[log in to unmask]> To: [log in to unmask] Sent: Thu, 20 Nov 2008 5:20 pm Subject: RE: [TN] black pad Hi Werner, I should have referred to your exact phrase, so you wouldn’t have to correct me J As far as the definition of BP is concerned, then I still prefer to define it as a manufacturing defect, which has nothing to do with the assembly process. The presence of thicker P-enriched layer isn’t a good thing but in true cases of BP it’s normal (thickn ess-wise) but the joints has almost zero strength. Regards, Vladimir From: [log in to unmask] [mailto:[log in to unmask]] Sent: Thursday, November 20, 2008 5:06 PM To: [log in to unmask]; Igoshev, Vladimir Subject: Re: [TN] black pad Hi Vladimir, I did not say 'excessive temperature'-- I said 'the more you expose an ENIG layer to soldering temperatures'--that means multiple or lengthy exposures. If you define 'Black Pad' as the presence of P at the Ni/NiSn-IMC interlayer to a degree significantly weakening that interface, then you can arrive at that condition by multiple paths. One is faulty manufacturing, the other is excessive Ni-dissolution--of course, these can work in combination. Werner -----Original Message----- From: Igoshev, Vladimir <[log in to unmask]> To: [log in to unmask] Sent: Thu, 20 Nov 2008 4:45 pm Subject: Re: [TN] black pad Well, with all due respect I would have to disagree with you Werner (not for the first time :-)). I wouldn't associate Black Pad with excessive soldering temperature. It's rather a board manufacturing related issue. Regards, Vladimir -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /* Sent: Thursday, November 20, 2008 4:38 PM 0A To: [log in to unmask] Subject: Re: [TN] black pad The more you expose an ENIG layer to soldering temperatures, the more Ni dissolves leaving more P at the layer between the Ni and the NiSn-IMC. The more? P the weaker this interface, leading to 'Black Pad' Werner -----Original Message----- From: henry rekers <[log in to unmask]> To: [log in to unmask] Sent: Thu, 20 Nov 2008 3:41 pm Subject: Re: [TN] black pad =0 A Can you give me any examples of black pad being caused by anything other than a "bad board"? ie.? Is there anything in processing "perfect board" that would cause a de-wet condition that indicates black pad??? I guess where I'm going is, can this be anything other than a supplier issue? --- On Thu, 11/20/08, Werner Engelmaier /* <[log in to unmask]> wrote: From: Werner Engelmaier /* <[log in to unmask]> Subject: Re: [TN] black pad To: [log in to unmask] Received: Thursday, November 20, 2008, 1:26 PM Hi 'rekers,' You canno t broad-brush like this. Some FAB houses do quite well, others not. ENIG, from various sources and at various conditions, has shown nickel corrosion or high phosphide concentrations. The underlying reasons for these are different, actually diametrically opposed. Some are the fault of the FAB house others not. Werner -----Original Message----- From: henry rekers <[log in to unmask]> To: [log in to unmask] Sent: Thu, 20 Nov 2008 12:45 pm =0 A Subject: [TN] black pad Anybody out there experiencing mass dewetting issues from North American board shops? ? From what I understand primary causes for dewetting (assuming the reflow/wave profile is bang on) is all on the board, ie nickel corrosion, degeneration of the nickel, or outgassing of the nickel/copper.? (I'm talking enig here.) ? Anybody? __________________________________________________________________ Connect with friends from any web browser - no download required. Try the new Yahoo! 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